I’ve order one BED for my project and I’m currently waiting for it. But now some doubts about my project are coming to my mind… :?
My plan is to use a small NEMA 11 [stepper to drive a big knob by using a 5 to 1 spur gear (the stepper motor has to be small because of space problems).
In this project, I want to let the operator to manually set the knob position in some “emergency” situation by applying a significant force even when the motor is fully powered and stationary on a given position.
As I know, when the windings are not energized, an inductive “kickback” of current occurs when the motor is manually rotated and acting as a generator. In my case, a rapid 90 degree rotation of the knob corresponds to around 1.25 turns of the stepper shaft. So I think that some kind of protection is necessary.
What is the situation when the windings are fully powered? The kickback is greater or not? Do I need additional protection in such case?
By googling I found the protection circuit below for a bipolar stepper:
Later I discovered that there are also some integrated circuits implementing such 8-diodes-array available on the market. For example [this one from STmicroelectronics.
Unfortunately I got rapidly lost in what the market offer, mainly because I don’t know exactly what will be the max overvoltage peak and the intensity of the inductive current trying to go back to the driver.
I do not even know if a bunch of diodes can solve my kickback problem… Any idea or suggestion? :?](https://www.st.com/en/protection-devices/da108s1.html)](Safety-Diodes hosted at ImgBB — ImgBB)](https://www.orientalmotor.de/Products/Stepper_motors/Stepper_motors/high_torque_2phase_motors_pkp/?arid=23564)
